JP4431891B2 - Piezoelectric element, piezoelectric actuator, piezoelectric pump, ink jet recording head, ink jet printer, surface acoustic wave element, thin film piezoelectric resonator, frequency filter, oscillator, electronic circuit, and electronic equipment - Google Patents

Description

  The present invention relates to a piezoelectric element, a piezoelectric actuator, a piezoelectric pump, an ink jet recording head, an ink jet printer, a surface acoustic wave element, a thin film piezoelectric resonator, a frequency filter, an oscillator, an electronic circuit, and an electronic apparatus.

Inkjet printers are known as printers that enable high image quality and high-speed printing. The ink jet printer includes an ink jet recording head having a cavity whose internal volume changes, and performs printing by ejecting ink droplets from the nozzle while scanning the head. As a head actuator in an ink jet recording head for such an ink jet printer, a piezoelectric element using a piezoelectric layer represented by PZT (Pb (Zr, Ti) O ₃ ) has been conventionally used (for example, JP, 2001-223404, A).

In addition, in other devices having a piezoelectric layer, since improvement in the characteristics is desired, provision of a piezoelectric layer having good piezoelectric characteristics is desired.
JP 2001-223404 A

  An object of the present invention is to provide a piezoelectric element capable of obtaining good piezoelectric characteristics. Another object of the present invention is to provide a piezoelectric actuator, a piezoelectric pump, an ink jet recording head, an ink jet printer, a surface acoustic wave element, a thin film piezoelectric resonator, a frequency filter, an oscillator, an electronic circuit, and an electronic device using the piezoelectric element. To provide equipment.

The piezoelectric element according to the first aspect of the present invention is
A substrate,
A first conductive layer formed above the substrate;
A piezoelectric layer made of a piezoelectric material having a perovskite structure formed above the first conductive layer;
A second conductive layer electrically connected to the piezoelectric layer,
The first conductive layer includes one or more buffer layers made of a lanthanum-based layered perovskite compound preferentially oriented to (001).

  According to this piezoelectric element, good piezoelectric characteristics can be obtained. The reason for this is as follows.

  This piezoelectric element has a buffer layer made of a lanthanum-based layered perovskite compound (hereinafter also referred to as “La layered compound”). Since the La layered compound has a layered structure, it can be easily preferentially oriented to (001) without depending on the crystal orientation of the material constituting the underlying layer. That is, the buffer layer is hardly mixed with crystals of an La layer compound oriented in (111), (110), etc., for example. As described above, since most of the crystals of the La layer compound are oriented to (001), when the piezoelectric layer is formed above the buffer layer, the piezoelectric layer takes over the crystal orientation of the buffer layer. , (001). As a result, the piezoelectric element can have a piezoelectric layer that has a high piezoelectric constant and is greatly deformed with respect to the applied voltage. That is, according to this piezoelectric element, good piezoelectric characteristics can be obtained.

  In the present invention, the “piezoelectric body having a perovskite structure” includes a piezoelectric body having a perovskite structure and a piezoelectric body having a layered perovskite structure.

  In the present invention, “preferential orientation” means that 100% of crystals are in a desired orientation (for example, (001) orientation), and most crystals (for example, 90% or more) are oriented in a desired orientation. And the remaining crystals are in other orientations (for example, (111) orientation).

  Further, in the present invention, other specific objects (hereinafter referred to as “B”) formed above a specific object (hereinafter referred to as “A”) are B directly formed on A and A And B formed via the others on A. Further, in the present invention, forming B above A includes a case where B is formed directly on A and a case where B is formed on A via another on A.

In the piezoelectric element according to the present invention,
The lanthanum-based layered perovskite compound is La ₂ NiO ₄ , La ₃ Ni ₂ O ₇ , La ₄ Ni ₃ O ₁₀ , La ₂ CuO ₄ , and at least one of at least two of these solid solutions. Species can be included.

In the piezoelectric element according to the present invention,
The first conductive layer may include one or more low resistance layers made of a conductive material having a specific resistance lower than that of the lanthanum-based layered perovskite compound.

In the piezoelectric element according to the present invention,
The conductive material includes at least one of a metal, an oxide of the metal, and an alloy made of the metal,
The metal may be at least one of Pt, Ir, Ru, Ag, Au, Cu, Al, and Ni.

In the piezoelectric element according to the present invention,
The first conductive layer includes
The low resistance layer;
And the buffer layer formed above the low resistance layer.

In the piezoelectric element according to the present invention,
The first conductive layer includes one or more conductive oxide layers made of a conductive oxide having a perovskite structure,
The conductive oxide may be preferentially oriented to (001).

In the piezoelectric element according to the present invention,
The first conductive layer includes
The buffer layer;
And the conductive oxide layer formed above the buffer layer.

In the piezoelectric element according to the present invention,
The first conductive layer includes
The low resistance layer;
The buffer layer formed above the low resistance layer;
A conductive oxide layer formed above the buffer layer and made of a conductive oxide having a perovskite structure;
The conductive oxide may be preferentially oriented to (001).

In the piezoelectric element according to the present invention,
The conductive oxide includes CaRuO ₃ , SrRuO ₃ , BaRuO ₃ , SrVO ₃ , (La, Sr) MnO ₃ , (La, Sr) CrO ₃ , (La, Sr) CoO ₃ , and LaNiO ₃ , and these At least one of solid solutions consisting of at least two of the above can be included.

In the piezoelectric element according to the present invention,
The piezoelectric body is represented by a general formula of ABO ₃ ,
A includes Pb,
B can include at least one of Zr and Ti.

In the piezoelectric element according to the present invention,
The B may further contain Nb.

In the piezoelectric element according to the present invention,
The piezoelectric body may be a rhombohedral crystal or a mixed crystal of a tetragonal crystal and a rhombohedral crystal and preferentially oriented to (001).

The piezoelectric element according to the second aspect of the present invention is
A substrate,
A first conductive layer formed above the substrate;
A piezoelectric layer having a perovskite structure formed above the first conductive layer;
A second conductive layer electrically connected to the piezoelectric layer,
The first conductive layer includes
One or more conductive oxide layers made of a conductive oxide having a perovskite structure;
One or more low resistance layers made of a conductive material having a specific resistance lower than that of the conductive oxide, and
The conductive oxide is preferentially oriented to (001).

  The piezoelectric actuator according to the present invention has the above-described piezoelectric element.

  The piezoelectric pump according to the present invention has the above-described piezoelectric element.

  An ink jet recording head according to the present invention includes the above-described piezoelectric element.

  An ink jet printer according to the present invention has the above-described ink jet recording head.

  A surface acoustic wave device according to the present invention includes the above-described piezoelectric device.

  A thin film piezoelectric resonator according to the present invention includes the above-described piezoelectric element.

  The frequency filter according to the present invention has at least one of the surface acoustic wave element and the thin film piezoelectric resonator.

  The oscillator according to the present invention includes at least one of the above-described surface acoustic wave device and the above-described thin film piezoelectric resonator.

  The electronic circuit according to the present invention includes at least one of the above-described frequency filter and the above-described oscillator.

  The electronic device according to the present invention includes at least one of the above-described piezoelectric pump and the above-described electronic circuit.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

1. 1. First embodiment 1-1. First, the piezoelectric element 10 according to the first embodiment will be described.

  FIG. 1 is a cross-sectional view showing the piezoelectric element 10. The piezoelectric element 10 includes a substrate 1, a stopper layer 2 formed on the substrate 1, a hard layer 3 formed on the stopper layer 2, and a first conductive layer 4 formed on the hard layer 3. And a piezoelectric layer 5 formed on the first conductive layer 4 and a second conductive layer 6 formed on the piezoelectric layer 5.

  As the substrate 1, for example, a (110) oriented silicon substrate can be used. As the stopper layer 2, for example, a silicon oxide layer can be used. The stopper layer 2 can function as an etching stopper, for example, in the step of etching the substrate 1 from the back side in order to form the ink cavity 521 of the ink jet recording head 50 (see FIG. 9). The stopper layer 2 and the hard layer 3 function as an elastic layer 55 in the ink jet recording head 50. For the hard layer 3, for example, yttria-stabilized zirconia, cerium oxide, zirconium oxide, or the like can be used.

  The first conductive layer 4 includes a low resistance layer 40, a buffer layer 41 formed on the low resistance layer 40, and a conductive oxide layer 42 formed on the buffer layer 41. The first conductive layer 4 is one electrode for applying a voltage to the piezoelectric layer 5. For example, the first conductive layer 4 can be formed in the same planar shape as the piezoelectric layer 5.

The low resistance layer 40 is made of a conductive material having a specific resistance lower than that of the La layered compound. The conductive material can include, for example, at least one of a metal, an oxide of the metal, and an alloy made of the metal. Here, as the metal, for example, at least one of Pt, Ir, Ru, Ag, Au, Cu, Al, and Ni can be used. Examples of the metal oxide include IrO ₂ and RuO ₂ . Examples of the metal alloy include Pt—Ir, Ir—Al, Ir—Ti, Pt—Ir—Al, Pt—Ir—Ti, Pt—Ir—Al—Ti, and the like. In this embodiment, the crystal orientation of the conductive material is not particularly limited, and can be, for example, (111) oriented. The film thickness of the low resistance layer 40 can be, for example, about 50 nm to 150 nm.

The buffer layer 41 can be made of a lanthanum-based layered perovskite compound (La layered compound) preferentially oriented to (001). The La layer compound is, for example, at least one of La ₂ NiO ₄ , La ₃ Ni ₂ O ₇ , La ₄ Ni ₃ O ₁₀ , La ₂ CuO ₄ , and a solid solution composed of at least two of these. Can be included. The A site of the La layered compound is preferably substituted by Pb. Thereby, the crystallization temperature can be lowered. This is particularly effective when the buffer layer 41 is formed by a sol-gel method. Considering the conductivity of the buffer layer 41, the amount replaced by Pb can be, for example, 10 at% or less. The film thickness of the buffer layer 41 can be about 10 nm to 50 nm, for example.

The conductive oxide layer 42 is made of a conductive oxide having a perovskite structure. The conductive oxide is preferentially oriented to (001). Note that the crystal orientation in the in-plane direction of the conductive oxide is random. Examples of the conductive oxide include CaRuO ₃ , SrRuO ₃ , BaRuO ₃ , SrVO ₃ , (La, Sr) MnO ₃ , (La, Sr) CrO ₃ , (La, Sr) CoO ₃ , and LaNiO ₃ , and At least one of solid solutions composed of at least two of these can be included. In particular, LaNiO ₃ is preferable because it is easy to self-orient at (001). Here, the A site of LaNiO ₃ is preferably substituted by Pb. Thereby, the crystallization temperature can be lowered. This is particularly effective when the conductive oxide layer 42 is formed by the sol-gel method. Further, by replacing the A site with Pb, the lattice constant of the conductive oxide can be brought close to the lattice constant of the piezoelectric body constituting the piezoelectric layer 5. That is, lattice mismatch between the conductive oxide layer 42 and the piezoelectric layer 5 can be reduced. Considering the conductivity of the conductive oxide layer 42, the amount of substitution of the A site by Pb can be, for example, 10 at% or less. The film thickness of the conductive oxide layer 42 can be set to, for example, about 0 nm to 140 nm.

  The piezoelectric layer 5 is made of a piezoelectric body having a perovskite structure. The piezoelectric body constituting the piezoelectric layer 5 is preferably a rhombohedral crystal or a mixed crystal of tetragonal and rhombohedral crystals and preferentially oriented to (001). The piezoelectric layer 5 made of such a piezoelectric body has a high piezoelectric constant.

This piezoelectric body can be represented by, for example, a general formula of ABO ₃ . Here, A can include Pb, and B can include at least one of Zr and Ti. Furthermore, B can also contain at least one of V, Nb, and Ta. In this case, the piezoelectric body can include at least one of Si and Ge. More specifically, the piezoelectric body includes, for example, lead zirconate titanate (Pb (Zr, Ti) O ₃ ), lead niobate zirconate titanate (Pb (Zr, Ti, Nb) O ₃ ), titanate. Lead lanthanum ((Pb, La) TiO ₃ ), lead lanthanum zirconate titanate ((Pb, La) ZrTiO ₃ ), lead magnesium niobate titanate (Pb (Mg, Nb) TiO ₃ ), magnesium niobate zirconate Lead titanate (Pb (Mg, Nb) (Zr, Ti) O ₃ ), lead zinc niobate titanate (Pb (Zn, Nb) TiO ₃ ), scandium lead niobate titanate (Pb (Sc, Nb) TiO 3 ₃ ) and at least one of lead nickel niobate titanate (Pb (Ni, Nb) TiO ₃ ). Lead zirconate titanate niobate (Pb (Zr, Ti, Nb) O ₃ ) is, for example, Zr of B site of lead zirconate titanate (Pb (Zr _x Ti _y ) O ₃ (x + y = 1)). A part thereof is substituted with Nb, and can be represented by Pb (Zr _x-z Nb _z Ti _y ) O ₃ . Here, the composition ratio of the B site is
0.4 ≦ x ≦ 0.6
0.6 ≧ y ≧ 0.4
0 <z ≦ 0.3
It is preferable that If x, y, and z are within the above ranges, x, y, and z are values at the phase boundary (MPB: Morphotropic Phase Boundary) of the crystal structure of the piezoelectric layer 5 or values near the MPB. A phase boundary is a boundary where rhombohedral and tetragonal phase transition. The piezoelectric constant (d ₃₁ ) has a maximum value near the phase boundary. Therefore, if x, y, and z are within the above ranges, the piezoelectric layer 5 can be easily controlled to be rhombohedral or a mixed crystal of tetragonal and rhombohedral, and high piezoelectric characteristics can be obtained. It can be expressed.

The piezoelectric body may be, for example, (Ba _1-x Sr _x ) TiO ₃ (0 ≦ x ≦ 0.3), Bi ₄ Ti ₃ O ₁₂ , SrBi ₂ Ta ₂ O ₉ , LiNbO ₃ , LiTaO ₃ , and At least one of KNbO ₃ may be included. The film thickness of the piezoelectric layer 5 can be set to, for example, about 400 nm to 5000 nm.

  The second conductive layer 6 includes another conductive oxide layer (hereinafter referred to as “second conductive oxide layer”) 46 and another low-resistance layer (on the second conductive oxide layer 46). Hereinafter referred to as “second low resistance layer”) 47. The second conductive layer 6 is the other electrode for applying a voltage to the piezoelectric layer 5. Since the second conductive layer 6 includes the second conductive oxide layer 46 and the second low resistance layer 47, the second conductive layer 6 and the first conductive layer 4 are substantially symmetrical with respect to the piezoelectric layer 5. Can be. That is, the symmetry of the piezoelectric element 10 can be improved. Note that the second conductive layer 6 may be composed of either the second conductive oxide layer 46 or the second low resistance layer 47. For example, the second conductive layer 6 can be formed in the same planar shape as the piezoelectric layer 5.

  The second conductive oxide layer 46 can be made of, for example, a conductive oxide having a perovskite structure (hereinafter referred to as “second conductive oxide”). As the second conductive oxide, for example, the conductive oxide constituting the conductive oxide layer 42 described above can be used. The film thickness of the second conductive oxide layer 46 can be, for example, about 0 nm to 200 nm.

  The second low resistance layer 47 can be made of a conductive material having a specific resistance lower than that of the second conductive oxide, for example. As this conductive material, for example, the conductive material constituting the low-resistance layer 40 described above can be used. The film thickness of the second low resistance layer 47 can be set to, for example, about 0 nm to 200 nm.

  1-2. Next, a method for manufacturing the piezoelectric element 10 according to the present embodiment will be described with reference to FIG.

  First, a (110) -oriented silicon substrate is prepared as the substrate 1.

  Next, the stopper layer 2 is formed on the substrate 1. The stopper layer 2 can be formed by, for example, a thermal oxidation method, a CVD method, or the like.

  Next, the hard layer 3 is formed on the stopper layer 2. The hard layer 3 can be formed by, for example, a CVD method, a sputtering method, a vapor deposition method, or the like.

  Next, the low resistance layer 40 is formed on the hard layer 3. As described above, in this embodiment, the crystal orientation of the conductive material constituting the low resistance layer 40 is not particularly limited, and therefore the conditions and method for manufacturing the low resistance layer 40 can be selected as appropriate. For example, the low resistance layer 40 can be formed by sputtering, vacuum deposition, or the like. The temperature at which the low resistance layer 40 is formed can be, for example, about room temperature to 600 ° C.

  Next, the buffer layer 41 is formed on the low resistance layer 40. The buffer layer 41 can be formed by, for example, a sputtering method, a sol-gel method, a CVD method, a laser ablation method, a molecular beam epitaxy method, or the like. The temperature at which the buffer layer 41 is formed can be, for example, about 250 ° C. to 500 ° C.

  Next, a conductive oxide layer 42 is formed on the buffer layer 41. The conductive oxide layer 42 can be formed by, for example, a sputtering method, a sol-gel method, or the like. Through the above steps, the first conductive layer 4 is formed.

  Next, the piezoelectric layer 5 is formed on the conductive oxide layer 42. The piezoelectric layer 5 can be formed by, for example, a sputtering method or a sol-gel method.

  Next, a second conductive oxide layer 46 is formed on the piezoelectric layer 5. The second conductive oxide layer 46 can be formed by, for example, a sputtering method, a sol-gel method, or the like.

  Next, a second low resistance layer 47 is formed on the second conductive oxide layer 46. The second low resistance layer 47 can be formed by, for example, sputtering, vacuum deposition, or the like. Through the above steps, the second conductive layer 6 is formed.

  Through the above steps, the piezoelectric element 10 according to this embodiment can be manufactured.

  1-3. According to the piezoelectric element 10 according to the present embodiment, good piezoelectric characteristics can be obtained. The reason for this is as follows.

  The piezoelectric element 10 according to the present embodiment has a buffer layer 41 made of an La layer compound. Since the La layered compound has a layered structure, it can be easily preferentially oriented to (001) without depending on the crystal orientation of the conductive material constituting the underlying low resistance layer 40. That is, in the buffer layer 41, for example, there is almost no mixing of crystals of an La layered compound oriented in (111), (110) or the like. Thus, since most of the crystals of the La layer compound are oriented to (001), when the conductive oxide layer 42 is formed on the buffer layer 41, the conductive oxide layer 42 By taking over the crystal orientation of (001), it can be preferentially oriented to (001). When the piezoelectric layer 5 is formed on the conductive oxide layer 42, the piezoelectric layer 5 can take over the crystal orientation of the conductive oxide layer 42 and be preferentially oriented to (001). Thus, the piezoelectric element 10 can have the piezoelectric layer 5 having a high piezoelectric constant and undergoing a large deformation with respect to the applied voltage. That is, according to the piezoelectric element 10 according to the present embodiment, good piezoelectric characteristics can be obtained.

Further, as described above, the conductive oxide layer 42 is preferably made of LaNiO ₃ that is easily self-oriented at (001). However, for example, when not forming a buffer layer 41 as an underlying conductive oxide layer 42, depending on the manufacturing conditions and the manufacturing method for LaNiO _3, the conductive oxide layer 42, crystals of LaNiO ₃ oriented in such (110) May be mixed. On the other hand, according to the method for manufacturing the piezoelectric element 10 according to the present embodiment, the conductive oxide layer 42 is formed using the buffer layer 41 made of the La layered compound as a base as described above, so that LaNiO ₃ is more reliable. And (001) can be self-oriented. Thereby, when the piezoelectric layer 5 is formed on the conductive oxide layer 42 made of LaNiO ₃ , more of the crystals constituting the piezoelectric layer 5 take over the crystal orientation of the conductive oxide layer 42, It can be oriented to (001).

  In the piezoelectric element 10 according to this embodiment, the piezoelectric layer 5 is formed on the conductive oxide layer 42. That is, the material of the conductive oxide layer 42 can be appropriately selected according to the type of material of the piezoelectric layer 5. Thereby, for example, the lattice constant of the piezoelectric body constituting the piezoelectric layer 5 and the lattice constant of the conductive oxide constituting the conductive oxide layer 42 can be made substantially the same. That is, lattice mismatch between the piezoelectric layer 5 and the conductive oxide layer 42 can be reduced. As a result, the stress applied to the piezoelectric layer 5 can be reduced.

  In the piezoelectric element 10 according to the present embodiment, the first conductive layer 4 includes the low resistance layer 40. The low resistance layer 40 is made of a conductive material having a specific resistance lower than that of the La layered compound. Thereby, for example, when comparing the case where the first conductive layer 4 does not have the low resistance layer 40 and the case where the first conductive layer 4 has the low resistance layer 40 with the first conductive layer 4 having the same shape, When the first conductive layer 4 has the low resistance layer 40 (that is, in the case of the present embodiment), the resistance of the first conductive layer 4 as a whole is smaller. Therefore, according to the piezoelectric element 10 according to the present embodiment, good piezoelectric characteristics can be obtained.

  1-4. Next, a modification of the piezoelectric element 10 according to the present embodiment will be described with reference to the drawings. Note that differences from the piezoelectric element 10 shown in FIG. 1 described above will be described, and description of similar points will be omitted. 2-6 is sectional drawing which shows typically an example of the modification of the piezoelectric element 10, respectively.

  For example, as shown in FIG. 2, the first conductive layer 4 can have no conductive oxide layer 42. That is, the first conductive layer 4 can be composed of the low resistance layer 40 and the buffer layer 41. In this case, when the piezoelectric layer 5 is formed on the buffer layer 41, the piezoelectric layer 5 can take over the crystal orientation of the buffer layer 41 and be preferentially oriented to (001).

  For example, as shown in FIG. 2, the second conductive layer 6 can be composed of only the second low resistance layer 47. For example, although not shown, the second conductive layer 6 can be composed of only the second conductive oxide layer 46. In these cases, the second conductive layer 6 and the first conductive layer 4 can be made substantially symmetrical with respect to the piezoelectric layer 5.

  For example, as shown in FIG. 3, the first conductive layer 4 may not have the low resistance layer 40. That is, the first conductive layer 4 can include a buffer layer 41 and a conductive oxide layer 42.

  Further, for example, as shown in FIG. 4, the first conductive layer 4 may not include the low resistance layer 40 and the conductive oxide layer 42. That is, the first conductive layer 4 can be composed only of the buffer layer 41.

  Further, for example, as shown in FIG. 5, the first conductive layer 4 can be composed of two buffer layers 41 and a low resistance layer 40 sandwiched between them. For example, although not shown, the first conductive layer 4 can be composed of two buffer layers 41 and a conductive oxide layer 42 sandwiched between them.

  For example, as shown in FIG. 6, the first conductive layer 4 is formed on the buffer layer 41, the conductive oxide layer 42 formed on the buffer layer 41, and the conductive oxide layer 42. And a low resistance layer 40. In this case, when the low resistance layer 40 is formed on the conductive oxide layer 42, the low resistance layer 40 can take over the crystal orientation of the conductive oxide layer 42 and be preferentially oriented to (001). The temperature at which the low resistance layer 40 is formed can be, for example, about 600 ° C. to 700 ° C. When the piezoelectric layer 5 is formed on the low resistance layer 40, the piezoelectric layer 5 can take over the crystal orientation of the low resistance layer 40 and be preferentially oriented to (001).

  For example, as shown in FIG. 7, the first conductive layer 4 can include a buffer layer 41 and a low-resistance layer 40 formed on the buffer layer 41.

For example, as shown in FIG. 8, the first conductive layer 4 can include a low resistance layer 40 and a conductive oxide layer 42 formed on the low resistance layer 40. In this case, when the piezoelectric layer 5 is formed on the conductive oxide layer 42, the piezoelectric layer 5 can take over the crystal orientation of the conductive oxide layer 42 and be preferentially oriented to (001). The conductive oxide layer 42 can be made of a conductive oxide (for example, LaNiO ₃ or the like) that is easily self-oriented to (001).

For example, although not shown, the first conductive layer 4 can include a conductive oxide layer 42 and a low-resistance layer 40 formed on the conductive oxide layer 42. In this case, when the low resistance layer 40 is formed on the conductive oxide layer 42, the low resistance layer 40 can take over the crystal orientation of the conductive oxide layer 42 and be preferentially oriented to (001). The conductive oxide layer 42 can be made of a conductive oxide (for example, LaNiO ₃ or the like) that is easily self-oriented to (001). When the piezoelectric layer 5 is formed on the low resistance layer 40, the piezoelectric layer 5 can take over the crystal orientation of the low resistance layer 40 and be preferentially oriented to (001).

  Note that the above-described modifications are merely examples, and are not limited thereto. For example, the stacking order of each layer, the number of layers, and the like can be appropriately changed.

2. Second embodiment 2-1. Next, an embodiment of an ink jet recording head having the piezoelectric element 10 according to the first embodiment will be described. FIG. 9 is a side sectional view showing a schematic configuration of the ink jet recording head according to the present embodiment, and FIG. 10 is an exploded perspective view of the ink jet recording head. In addition, FIG. 10 is shown upside down from the state normally used.

  As shown in FIG. 9, the ink jet recording head (hereinafter also referred to as “head”) 50 includes a head main body 57 and a piezoelectric portion 54 provided on the head main body 57. 9 corresponds to the first conductive layer 4, the piezoelectric layer 5, and the second conductive layer 6 in the piezoelectric element 10 shown in FIG. In the ink jet recording head according to the present embodiment, the piezoelectric element 10 can function as a piezoelectric actuator. A piezoelectric actuator is an element having a function of moving a certain object.

  Further, the stopper layer 2 and the hard layer 3 in the piezoelectric element 10 shown in FIG. 1 correspond to the elastic layer 55 in FIG. The substrate 1 (see FIG. 1) constitutes a main part of the head main body 57.

  That is, the head 50 includes a nozzle plate 51, an ink chamber substrate 52, an elastic layer 55, and a piezoelectric part (vibration source) 54 bonded to the elastic layer 55 as shown in FIG. 56 is housed. The head 50 constitutes an on-demand piezo jet head.

  The nozzle plate 51 is composed of, for example, a stainless steel rolling plate or the like, and has a large number of nozzles 511 for ejecting ink droplets formed in a line. The pitch between these nozzles 511 is appropriately set according to the printing accuracy.

  An ink chamber substrate 52 is fixed (fixed) to the nozzle plate 51. The ink chamber substrate 52 is formed by the substrate 1 (see FIG. 1). The ink chamber substrate 52 has a plurality of cavities (ink cavities) 521, a reservoir 523, and a supply port 524 formed by a nozzle plate 51, side walls (partition walls) 522, and an elastic layer 55. . The reservoir 523 temporarily stores ink supplied from the ink cartridge 631 (see FIG. 13). Ink is supplied from the reservoir 523 to each cavity 521 through the supply port 524.

  As shown in FIGS. 9 and 10, the cavity 521 is disposed corresponding to each nozzle 511. The cavities 521 each have a variable volume due to the vibration of the elastic layer 55. The cavity 521 is configured to eject ink by this volume change.

  As a base material for obtaining the ink chamber substrate 52, that is, the substrate 1 (see FIG. 1), a (110) -oriented silicon single crystal substrate is used. Since this (110) -oriented silicon single crystal substrate is suitable for anisotropic etching, the ink chamber substrate 52 can be formed easily and reliably.

  An elastic layer 55 is disposed on the side of the ink chamber substrate 52 opposite to the nozzle plate 51. Further, a plurality of piezoelectric portions 54 are provided on the side of the elastic layer 55 opposite to the ink chamber substrate 52. As shown in FIG. 10, a communication hole 531 is formed at a predetermined position of the elastic layer 55 so as to penetrate in the thickness direction of the elastic layer 55. Ink is supplied from the ink cartridge 631 to the reservoir 523 through the communication hole 531.

  Each piezoelectric portion 54 is electrically connected to a piezoelectric element driving circuit described later, and is configured to operate (vibrate, deform) based on a signal from the piezoelectric element driving circuit. That is, each piezoelectric part 54 functions as a vibration source (head actuator). The elastic layer 55 vibrates (deflection) due to the vibration (deflection) of the piezoelectric portion 54 and functions to instantaneously increase the internal pressure of the cavity 521.

  The base 56 is made of, for example, various resin materials, various metal materials, or the like. As shown in FIG. 10, the ink chamber substrate 52 is fixed and supported on the base body 56.

  2-2. Next, the operation of the ink jet recording head 50 in this embodiment will be described. In the head 50 in the present embodiment, a voltage is applied between the first conductive layer 4 and the second conductive layer 6 of the piezoelectric portion 54 in a state where a predetermined ejection signal is not input via the piezoelectric element driving circuit. In a state where it is not performed, the piezoelectric layer 5 is not deformed as shown in FIG. For this reason, the elastic layer 55 is not deformed and the volume of the cavity 521 is not changed. Accordingly, no ink droplet is ejected from the nozzle 511.

  On the other hand, in a state where a predetermined ejection signal is input via the piezoelectric element driving circuit, that is, in a state where a voltage is applied between the first conductive layer 4 and the second conductive layer 6 of the piezoelectric portion 54, FIG. As shown in FIG. 4, the piezoelectric layer 5 undergoes a deflection deformation in the minor axis direction (the direction of the arrow s shown in FIG. 12). As a result, the elastic layer 55 bends and the volume of the cavity 521 changes. At this time, the pressure in the cavity 521 increases instantaneously, and the ink droplet 58 is ejected from the nozzle 511.

  That is, when a voltage is applied, the crystal lattice of the piezoelectric layer 5 is stretched in the direction perpendicular to the plane direction (the direction of the arrow d shown in FIG. 12), but is simultaneously compressed in the plane direction. In this state, the tensile stress f acts on the piezoelectric layer 5 in the plane. Therefore, the elastic layer 55 is deflected and bent by the tensile stress f. The greater the amount of displacement (absolute value) of the piezoelectric layer 5 in the minor axis direction of the cavity 521, the greater the amount of deflection of the elastic layer 55, making it possible to eject ink droplets more efficiently. .

  When the ejection of one ink is completed, the piezoelectric element driving circuit stops applying the voltage between the first conductive layer 4 and the second conductive layer 6. Thereby, the piezoelectric part 54 returns to the original shape shown in FIG. 11, and the volume of the cavity 521 increases. At this time, pressure (pressure in the positive direction) from the ink cartridge 631 toward the nozzle 511 acts on the ink. For this reason, air is prevented from entering the cavity 521 from the nozzle 511, and an amount of ink corresponding to the ink ejection amount is supplied from the ink cartridge 631 to the cavity 521 through the reservoir 523.

  In this way, arbitrary (desired) characters and figures are printed by sequentially inputting ejection signals via the piezoelectric element driving circuit to the piezoelectric unit 54 at the position where ink droplets are to be ejected. be able to.

  2-3. Next, an example of a method for manufacturing the ink jet recording head 50 in the present embodiment will be described.

  First, a base material to be an ink chamber substrate 52, that is, a substrate 1 made of a (110) oriented silicon single crystal substrate is prepared. Next, as shown in FIG. 1, the stopper layer 2, the hard layer 3, the first conductive layer 4, the piezoelectric layer 5, and the second conductive layer 6 are sequentially formed on the substrate 1.

  Next, the second conductive layer 6, the piezoelectric layer 5, and the first conductive layer 4 are patterned corresponding to the individual cavities 521 as shown in FIGS. 11 and 12, and as shown in FIG. The number of piezoelectric portions 54 corresponding to the number of cavities 521 is formed.

  Next, the base material (substrate 1) to be the ink chamber substrate 52 is patterned, and concave portions to be the cavities 521 are respectively provided at positions corresponding to the piezoelectric portions 54, and concave portions to be the reservoir 523 and the supply port 524 at predetermined positions. Form.

  In the present embodiment, since a (110) -oriented silicon substrate is used as the base material (substrate 1), wet etching (anisotropic etching) using a high-concentration alkaline aqueous solution is suitably employed. In the case of wet etching with a high-concentration alkaline aqueous solution, the stopper layer 2 can function as an etching stopper as described above. Therefore, the ink chamber substrate 52 can be formed more easily.

  Thus, the ink chamber substrate 52 is formed by removing the base material (substrate 1) by etching until the elastic layer 55 is exposed in the thickness direction. At this time, a portion left without being etched becomes the side wall 522.

  Next, the nozzle plate 51 on which the plurality of nozzles 511 are formed is aligned so that each nozzle 511 corresponds to a concave portion that becomes each cavity 521, and bonded in that state. Thereby, a plurality of cavities 521, a reservoir 523, and a plurality of supply ports 524 are formed. For the joining of the nozzle plate 51, for example, an adhesive method using an adhesive or a fusion method may be used. Next, the ink chamber substrate 52 is attached to the base 56.

  The ink jet recording head 50 according to this embodiment can be manufactured through the above steps.

2-4. According to the ink jet recording head 50 according to the present embodiment, as described above, the piezoelectric constant (d ₃₁ ) of the piezoelectric layer 5 of the piezoelectric portion 54 is high, and a greater deformation is caused with respect to the applied voltage. It has become. That is, the piezoelectric portion 54 has good piezoelectric characteristics. Thereby, the amount of deflection of the elastic layer 55 is increased, and ink droplets can be ejected more efficiently. Here, “efficient” means that the same amount of ink droplets can be ejected with a smaller voltage. That is, the driver circuit can be simplified and the power consumption can be reduced at the same time, so that the pitch of the nozzles 511 can be formed at a higher density. Therefore, high-density printing and high-speed printing are possible. Furthermore, since the length of the long axis of the cavity 521 can be shortened, the entire head can be reduced in size.

3. Third Embodiment 3-1. Next, an embodiment of an ink jet printer having the ink jet recording head 50 according to the second embodiment will be described. FIG. 13 is a schematic configuration diagram illustrating an inkjet printer 600 according to the present embodiment. The ink jet printer 600 can function as a printer that can print on paper or the like. In the following description, the upper side in FIG. 13 is referred to as “upper part” and the lower side is referred to as “lower part”.

  The ink jet printer 600 has an apparatus main body 620, a tray 621 for installing the recording paper P in the upper rear, a discharge port 622 for discharging the recording paper P in the lower front, and an operation panel 670 on the upper surface. Have.

  Inside the apparatus main body 620, there are mainly a printing apparatus 640 having a reciprocating head unit 630, a paper feeding apparatus 650 that feeds the recording paper P to the printing apparatus 640 one by one, the printing apparatus 640, and the paper feeding apparatus 650. And a control unit 660 for controlling.

  The printing apparatus 640 includes a head unit 630, a carriage motor 641 serving as a drive source for the head unit 630, and a reciprocating mechanism 642 that receives the rotation of the carriage motor 641 to reciprocate the head unit 630.

  The head unit 630 includes an ink jet recording head 50 having a large number of the nozzles 511 described above, an ink cartridge 631 that supplies ink to the ink jet recording head 50, and the ink jet recording head 50 and the ink cartridge 631. And a carriage 632 mounted thereon.

  The reciprocating mechanism 642 includes a carriage guide shaft 643 whose both ends are supported by a frame (not shown), and a timing belt 644 extending in parallel with the carriage guide shaft 643. The carriage 632 is supported by the carriage guide shaft 643 so as to reciprocate and is fixed to a part of the timing belt 644. When the timing belt 644 travels forward and backward through a pulley by the operation of the carriage motor 641, the head unit 630 reciprocates while being guided by the carriage guide shaft 643. During this reciprocation, ink is appropriately discharged from the ink jet recording head 50 and printing on the recording paper P is performed.

  The sheet feeding device 650 includes a sheet feeding motor 651 serving as a driving source thereof, and a sheet feeding roller 652 that rotates by the operation of the sheet feeding motor 651. The paper feed roller 652 is composed of a driven roller 652 a and a drive roller 652 b that are opposed to each other across the feeding path (recording paper P) of the recording paper P, and the driving roller 652 b is connected to the paper feeding motor 651. Has been.

  3-2. According to the ink jet printer 600 according to the present embodiment, as described above, since the ink jet recording head 50 having high performance and high nozzle density is provided, high density printing and high speed printing are possible.

  The ink jet printer 600 of the present invention can also be used as a droplet discharge device used industrially. In that case, as the ink to be ejected (liquid material), various functional materials can be used by adjusting them to an appropriate viscosity with a solvent or a dispersion medium.

4). Fourth embodiment 4-1. Next, an embodiment of a piezoelectric pump having the piezoelectric element 10 according to the first embodiment will be described with reference to the drawings. 14 and 15 are schematic cross-sectional views of the piezoelectric pump 20 according to the present embodiment. In the piezoelectric pump 20 according to the present embodiment, the piezoelectric element can function as a piezoelectric actuator. 14 and 15 includes the first conductive layer 4, the piezoelectric layer 5, and the second conductive layer 6 in the piezoelectric element 10 shown in FIG. 1, and the piezoelectric portion shown in FIG. The stopper layer 2 and the hard layer 3 in the element 10 are the diaphragm 24 in FIGS. 14 and 15. The substrate 1 (see FIG. 1) serves as a base 21 that constitutes a main part of the piezoelectric pump 20. The piezoelectric pump 20 includes a base 21, a piezoelectric unit 22, a pump chamber 23, a diaphragm 24, a suction side check valve 26a, a discharge side check valve 26b, a suction port 28a, and a discharge port 28b. Including.

  4-2. Next, the operation of the above piezoelectric pump will be described.

  First, when a voltage is supplied to the piezoelectric portion 22, a voltage is applied in the film thickness direction of the piezoelectric layer 5 (see FIG. 1). And as shown in FIG. 14, the piezoelectric part 22 bends in the direction (direction of arrow a shown in FIG. 14) where the pump chamber 23 spreads. Further, the diaphragm 24 together with the piezoelectric portion 22 bends in the direction in which the pump chamber 23 extends. For this reason, the pressure in the pump chamber 23 changes, and the fluid flows from the suction port 28a into the pump chamber 23 by the action of the check valves 26a and 26b (in the direction of arrow b shown in FIG. 14).

  Next, when the supply of voltage to the piezoelectric portion 22 is stopped, the application of voltage in the film thickness direction of the piezoelectric layer 5 (see FIG. 1) is stopped. And as shown in FIG. 15, the piezoelectric part 22 bends in the direction (direction of arrow a shown in FIG. 15) where the pump chamber 23 narrows. Further, the diaphragm 24 together with the piezoelectric portion 22 bends in the direction in which the pump chamber 23 narrows. For this reason, the pressure in the pump chamber 23 changes, and the fluid is discharged from the discharge port 28b to the outside by the action of the check valves 26a and 26b (in the direction of arrow b shown in FIG. 15).

  The piezoelectric pump 20 can be used as a water cooling module for electronic equipment, for example, a personal computer, preferably a notebook personal computer. The water cooling module uses the above-described piezoelectric pump 20 for driving the coolant, and has a structure including the piezoelectric pump 20 and a circulating water channel.

  4-3. According to the piezoelectric pump 20 according to the present embodiment, as described above, the piezoelectric layer 5 of the piezoelectric portion 22 has good piezoelectric characteristics, so that fluid can be sucked and discharged efficiently. Therefore, the piezoelectric pump 20 according to this embodiment can have a large discharge pressure and discharge amount. In addition, the piezoelectric pump 20 can be operated at high speed. Furthermore, the overall size of the piezoelectric pump 20 can be reduced.

5). Fifth embodiment 5-1. Next, an example of a surface acoustic wave device according to a fifth embodiment to which the present invention is applied will be described with reference to the drawings. As shown in FIG. 16, the surface acoustic wave device 30 as an example of this embodiment includes a substrate 11, a first conductive layer 14, a piezoelectric layer 15, a protective layer 17, a second conductive layer 16, including. The substrate 11, the first conductive layer 14, the piezoelectric layer 15, and the protective layer 17 constitute a base 18.

  As the substrate 11, for example, a (100) single crystal silicon substrate can be used. The first conductive layer 14 can be composed of the first conductive layer 4 in the piezoelectric element 10 shown in FIG. The piezoelectric layer 15 can be composed of the piezoelectric layer 5 in the piezoelectric element 10 shown in FIG. The protective layer 17 can be made of, for example, an oxide or a nitride. The protective layer 17 also functions as a temperature compensation layer. As the 2nd conductive layer 16, it can consist of the 2nd conductive layer 6 in the piezoelectric element 10 shown in FIG. The second conductive layer 16 is an inter-digital electrode (hereinafter referred to as “IDT electrode”). When observed from above, the second conductive layer 16 has a shape such as IDT electrodes 141, 142, 151, 152, and 153 shown in FIGS. A protective layer may be further formed on the IDT electrode.

  5-2. According to the surface acoustic wave device 30 according to the present embodiment, the piezoelectric layer 15 made of the piezoelectric layer 5 in the piezoelectric device 10 shown in FIG. It is also a high-performance one.

6). Sixth Embodiment 6-1. Next, an example of a frequency filter according to a sixth embodiment to which the present invention is applied will be described with reference to the drawings. FIG. 17 is a diagram schematically illustrating a frequency filter that is an example of the present embodiment.

  As shown in FIG. 17, the frequency filter has a base 140. As the substrate 140, the substrate 18 of the surface acoustic wave device 30 shown in FIG. 16 can be used.

  IDT electrodes 141 and 142 are formed on the upper surface of the substrate 140. Further, sound absorbing portions 143 and 144 are formed on the upper surface of the base 140 so as to sandwich the IDT electrodes 141 and 142. The sound absorbing parts 143 and 144 absorb surface acoustic waves that propagate on the surface of the base 140. A high frequency signal source 145 is connected to the IDT electrode 141 formed on the base 140, and a signal line is connected to the IDT electrode 142.

  6-2. Next, the operation of the above frequency filter will be described.

  In the above configuration, when a high frequency signal is output from the high frequency signal source 145, the high frequency signal is applied to the IDT electrode 141, thereby generating a surface acoustic wave on the upper surface of the substrate 140. The surface acoustic wave propagated from the IDT electrode 141 to the sound absorbing portion 143 side is absorbed by the sound absorbing portion 143. Of the surface acoustic waves propagated to the IDT electrode 142 side, the specific surface acoustic wave is determined according to the pitch of the IDT electrode 142 or the like. A surface acoustic wave having a frequency or a frequency in a specific band is converted into an electric signal and taken out to terminals 146a and 146b through signal lines. Note that most of the frequency components other than the specific frequency or the frequency in the specific band pass through the IDT electrode 142 and are absorbed by the sound absorbing unit 144. In this way, it is possible to obtain (filter) only a surface acoustic wave having a specific frequency or a specific band of the electric signal supplied to the IDT electrode 141 included in the frequency filter of the present embodiment.

7). Seventh Embodiment 7-1. Next, an example of an oscillator according to a seventh embodiment to which the present invention is applied will be described with reference to the drawings. FIG. 18 is a diagram schematically illustrating an oscillator which is an example of the present embodiment.

  As shown in FIG. 18, the oscillator has a base 150. As the base 150, the base 18 of the surface acoustic wave device 30 shown in FIG. 16 can be used as in the frequency filter described above.

  An IDT electrode 151 is formed on the upper surface of the substrate 150, and IDT electrodes 152 and 153 are formed so as to sandwich the IDT electrode 151. A high frequency signal source 154 is connected to one comb-like electrode 151a constituting the IDT electrode 151, and a signal line is connected to the other comb-like electrode 151b. The IDT electrode 151 corresponds to an electric signal applying electrode, and the IDT electrodes 152 and 153 are used for resonance to resonate a specific frequency component of a surface acoustic wave generated by the IDT electrode 151 or a frequency component of a specific band. It corresponds to an electrode.

  7-2. Next, the operation of the above oscillator will be described.

  In the above configuration, when a high-frequency signal is output from the high-frequency signal source 154, this high-frequency signal is applied to one comb-like electrode 151a of the IDT electrode 151, and thereby propagates to the IDT electrode 152 side on the upper surface of the base 150. The surface acoustic wave that propagates to the IDT electrode 153 side is generated. Among these surface acoustic waves, the surface acoustic wave having a specific frequency component is reflected by the IDT electrode 152 and the IDT electrode 153, and a standing wave is generated between the IDT electrode 152 and the IDT electrode 153. The surface acoustic wave having the specific frequency component is repeatedly reflected by the IDT electrodes 152 and 153, whereby the specific frequency component or the frequency component in the specific band resonates and the amplitude increases. A part of the surface acoustic wave of the specific frequency component or the frequency component of the specific band is extracted from the other comb-shaped electrode 151b of the IDT electrode 151, and corresponds to the resonance frequency of the IDT electrode 152 and the IDT electrode 153. An electric signal having a frequency (or a frequency having a certain band) can be taken out to the terminals 155a and 155b.

  7-3. 19 and 20 are diagrams schematically showing an example in which the above-described oscillator is applied to a VCSO (Voltage Controlled SAW Oscillator), FIG. 19 is a side perspective view, and FIG. It is a top perspective view.

  The VCSO is configured to be mounted inside a metal (Al or stainless steel) housing 60. An IC (Integrated Circuit) 62 and an oscillator 63 are mounted on the substrate 61. In this case, the IC 62 is an oscillation circuit that controls the frequency applied to the oscillator 63 in accordance with a voltage value input from an external circuit (not shown).

  In the oscillator 63, IDT electrodes 65a to 65c are formed on a base 64, and the configuration thereof is substantially the same as that of the oscillator shown in FIG. As the base body 64, the base body 18 of the surface acoustic wave device 30 shown in FIG. 16 can be used, similarly to the oscillator shown in FIG.

  A wiring 66 for electrically connecting the IC 62 and the oscillator 63 is patterned on the substrate 61. The IC 62 and the wiring 66 are connected by a wire line 67 such as a gold wire, for example, and the oscillator 63 and the wiring 66 are connected by a wire line 68 such as a gold wire. As a result, the IC 62 and the oscillator 63 are electrically connected via the wiring 66.

  The VCSO can also be formed by integrating the IC 62 and the oscillator 63 on the same substrate. FIG. 21 shows a schematic diagram of a VCSO in which an IC 62 and an oscillator 63 are integrated on the same substrate 61.

  As shown in FIG. 21, the VCSO is formed by sharing the substrate 61 in the IC 62 and the oscillator 63. As the substrate 61, for example, the substrate 11 of the surface acoustic wave device 30 shown in FIG. 16 can be used. Although not shown, the IC 62 and the electrode 65a of the oscillator 63 are electrically connected. As the electrode 65a, for example, the second conductive layer 16 of the surface acoustic wave element 30 shown in FIG. 16 can be used. As a transistor constituting the IC 62, a TFT (Thin Film Transistor) can be adopted.

  19 to 21 is used as, for example, a VCO (Voltage Controlled Oscillator) of the PLL circuit shown in FIG. Here, the PLL circuit will be briefly described.

  FIG. 22 is a block diagram showing a basic configuration of the PLL circuit. The PLL circuit includes a phase comparator 71, a low-pass filter 72, an amplifier 73, and a VCO 74. The phase comparator 71 compares the phase (or frequency) of the signal input from the input terminal 70 with the phase (or frequency) of the signal output from the VCO 74, and an error whose value is set according to the difference. A voltage signal is output. The low pass filter 72 passes only the low frequency component at the position of the error voltage signal output from the phase comparator 71. The amplifier 73 amplifies the signal output from the low-pass filter 72. The VCO 74 is an oscillation circuit in which the frequency that oscillates according to the input voltage value changes continuously within a certain range.

  Under such a configuration, the PLL circuit operates so that the difference between the phase (or frequency) input from the input terminal 70 and the phase (or frequency) of the signal output from the VCO 74 is reduced. Is synchronized with the frequency of the signal input from the input terminal 70. When the frequency of the signal output from the VCO 74 is synchronized with the frequency of the signal input from the input terminal 70, the frequency thereafter matches the signal input from the input terminal 70 except for a certain phase difference, and the input signal changes. A signal that follows the signal is output.

8). Eighth Embodiment Next, an example of an electronic circuit and an electronic apparatus according to an eighth embodiment to which the present invention is applied will be described with reference to the drawings. FIG. 23 is a block diagram illustrating an electrical configuration of an electronic device 300 that is an example of the present embodiment. The electronic device 300 is, for example, a mobile phone.

  The electronic device 300 includes an electronic circuit 310, a transmitter 80, a receiver 91, an input unit 94, a display unit 95, and an antenna unit 86. The electronic circuit 310 includes a transmission signal processing circuit 81, a transmission mixer 82, a transmission filter 83, a transmission power amplifier 84, a transmission / reception duplexer 85, a low noise amplifier 87, a reception filter 88, a reception mixer 89, a reception signal processing circuit 90, and a frequency. It has a synthesizer 92 and a control circuit 93.

  In the electronic circuit 310, the frequency filter shown in FIG. 17 can be used as the transmission filter 83 and the reception filter 88. The frequency to be filtered (frequency to be passed) is individually determined by the transmission filter 83 and the reception filter 88 according to the frequency required from the signal output from the transmission mixer 82 and the frequency required by the reception mixer 89. Is set. Further, as the VCO 74 of the PLL circuit (see FIG. 22) provided in the frequency synthesizer 92, the oscillator shown in FIG. 18 or the VCSO shown in FIGS. 19 to 21 can be used.

  The transmitter 80 is realized by, for example, a microphone that converts a sound wave signal into an electric signal. The transmission signal processing circuit 81 is a circuit that performs processing such as D / A conversion processing and modulation processing on the electrical signal output from the transmitter 80. The transmission mixer 82 mixes the signal output from the transmission signal processing circuit 81 using the signal output from the frequency synthesizer 92. The transmission filter 83 passes only a signal having a frequency that requires an intermediate frequency (hereinafter referred to as “IF”) and cuts a signal having an unnecessary frequency. A signal output from the transmission filter 83 is converted into an RF signal by a conversion circuit (not shown). The transmission power amplifier 84 amplifies the power of the RF signal output from the transmission filter 83 and outputs it to the transmission / reception duplexer 85.

  The transmitter / receiver demultiplexer 85 outputs the RF signal output from the transmission power amplifier 84 to the antenna unit 86 and transmits the RF signal from the antenna unit 86 in the form of a radio wave. The transmitter / receiver demultiplexer 85 demultiplexes the received signal received by the antenna unit 86 and outputs the demultiplexed signal to the low noise amplifier 87. The low noise amplifier 87 amplifies the received signal from the transmitter / receiver demultiplexer 85. The signal output from the low noise amplifier 87 is converted into IF by a conversion circuit (not shown).

  The reception filter 88 passes only a signal having a frequency necessary for IF converted by a conversion circuit (not shown), and cuts a signal having an unnecessary frequency. The reception mixer 89 uses the signal output from the frequency synthesizer 92 to mix the signal output from the reception filter 88. The reception signal processing circuit 90 is a circuit that performs processing such as A / D conversion processing and demodulation processing on the signal output from the reception mixer 89. The receiver 91 is realized by, for example, a small speaker that converts an electric signal into a sound wave.

  The frequency synthesizer 92 is a circuit that generates a signal supplied to the transmission mixer 82 and a signal supplied to the reception mixer 89. The frequency synthesizer 92 has a PLL circuit, and can divide a signal output from the PLL circuit to generate a new signal. The control circuit 93 controls the transmission signal processing circuit 81, the reception signal processing circuit 90, the frequency synthesizer 92, the input unit 94, and the display unit 95. For example, the display unit 95 displays the state of the device to the user of the mobile phone. The input unit 94 inputs an instruction from a user of a mobile phone, for example.

  In the above-described example, a mobile phone is used as the electronic device, and an electronic circuit provided in the mobile phone is used as the electronic circuit, and the present invention is not limited to the mobile phone. The present invention can be applied to a body communication device and an electronic circuit provided therein.

  Furthermore, the present invention can be applied not only to mobile communication devices but also to communication devices used in a stationary state such as tuners that receive BS and CS broadcasts, and electronic circuits provided therein. Furthermore, not only communication devices that use radio waves propagating in the air as communication carriers, but also electronic devices such as HUBs that use high-frequency signals propagating in coaxial cables or optical signals propagating in optical cables, and the electronics provided therein It can also be applied to circuits.

9. Ninth Embodiment Next, an example of a thin film piezoelectric resonator according to a ninth embodiment to which the present invention is applied will be described with reference to the drawings.

  9-1. FIG. 24 is a diagram schematically illustrating a first thin film piezoelectric resonator 700 which is an example of the present embodiment. The first thin film piezoelectric resonator 700 is a diaphragm type thin film piezoelectric resonator.

  The first thin film piezoelectric resonator 700 includes a substrate 701, an elastic layer 703, a first conductive layer 704, a piezoelectric layer 705, and a second conductive layer 706. The substrate 701, the elastic layer 703, the first conductive layer 704, the piezoelectric layer 705, and the second conductive layer 706 in the thin film piezoelectric resonator 700 are the substrate 1, the stopper layer 2, and the hard layer in the piezoelectric element 10 shown in FIG. 3 corresponds to the first conductive layer 4, the piezoelectric layer 5, and the second conductive layer 6. That is, the first thin film piezoelectric resonator 700 includes the piezoelectric element 10 shown in FIG. The elastic layer 703 corresponds to the stopper layer 2 and the hard layer 3.

  A via hole 702 that penetrates the substrate 701 is formed in the substrate 701. A wiring 708 is provided over the second conductive layer 706. The wiring 708 is electrically connected to an electrode 709 formed on the elastic layer 703 through a pad 710.

  9-2. According to the first thin-film piezoelectric resonator 700 according to this embodiment, the piezoelectric layer 705 has good piezoelectric characteristics, and thus has a high electromechanical coupling coefficient. Thereby, the thin film piezoelectric resonator 700 can be used in a high frequency region. Further, the thin film piezoelectric resonator 700 can be reduced in size (thinned) and can be operated satisfactorily.

  9-3. FIG. 25 is a diagram schematically showing a second thin film piezoelectric resonator 800 which is an example of the present embodiment. The second thin film piezoelectric resonator 800 is different from the first thin film piezoelectric resonator 700 shown in FIG. 24 mainly in that an air gap 802 is formed between the substrate 801 and the elastic layer 803 without forming a via hole. In the point.

  The second thin film piezoelectric resonator 800 includes a substrate 801, an elastic layer 803, a first conductive layer 804, a piezoelectric layer 805, and a second conductive layer 806. The substrate 801, the elastic layer 803, the first conductive layer 804, the piezoelectric layer 805, and the second conductive layer 806 in the thin film piezoelectric resonator 800 are the substrate 1, the stopper layer 2, and the hard layer in the piezoelectric element 10 shown in FIG. 3 corresponds to the first conductive layer 4, the piezoelectric layer 5, and the second conductive layer 6. That is, the second thin film piezoelectric resonator 800 has the piezoelectric element 10 shown in FIG. The elastic layer 803 corresponds to the stopper layer 2 and the hard layer 3. The air gap 802 is a space formed between the substrate 801 and the elastic layer 803.

  9-4. According to the second thin film piezoelectric resonator 800 according to the present embodiment, the piezoelectric layer 805 has good piezoelectric characteristics, and thus has a high electromechanical coupling coefficient. Thereby, the thin film piezoelectric resonator 800 can be used in a high frequency region. Further, the thin film piezoelectric resonator 800 can be reduced in size (thinned) and can be operated satisfactorily.

  9-5. The piezoelectric thin film resonator according to this embodiment (for example, the first thin film piezoelectric resonator 700 and the second thin film piezoelectric resonator 800) can function as a resonator, a frequency filter, or an oscillator. For example, in the electronic circuit 310 shown in FIG. 23, as the transmission filter 83 and the reception filter 88, the piezoelectric thin film resonator according to the present embodiment functioning as a frequency filter can be used. In addition, as the oscillator included in the frequency synthesizer 92, the piezoelectric thin film resonator according to the present embodiment functioning as an oscillator can be used.

  Although the embodiments of the present invention have been described in detail as described above, those skilled in the art will readily understand that many variations are possible without substantially departing from the novel matters and effects of the present invention. . Accordingly, all such modifications are intended to be included in the scope of the present invention. For example, the piezoelectric element according to the present invention is applicable not only to the above-described device but also to various devices. For example, the piezoelectric element according to the present invention can be used as a piezoelectric actuator for driving a lens in an optical zoom mechanism of a camera (including those mounted on a mobile phone or a PDA: Personal Digital Assistant).

1 is a cross-sectional view schematically showing a piezoelectric element according to a first embodiment. Sectional drawing which shows typically an example of the modification of the piezoelectric element which concerns on 1st Embodiment. Sectional drawing which shows typically an example of the modification of the piezoelectric element which concerns on 1st Embodiment. Sectional drawing which shows typically an example of the modification of the piezoelectric element which concerns on 1st Embodiment. Sectional drawing which shows typically an example of the modification of the piezoelectric element which concerns on 1st Embodiment. Sectional drawing which shows typically an example of the modification of the piezoelectric element which concerns on 1st Embodiment. Sectional drawing which shows typically an example of the modification of the piezoelectric element which concerns on 1st Embodiment. Sectional drawing which shows typically an example of the modification of the piezoelectric element which concerns on 1st Embodiment. FIG. 5 is a schematic configuration diagram of an ink jet recording head according to a second embodiment. FIG. 6 is an exploded perspective view of an ink jet recording head according to a second embodiment. FIG. 4 is a diagram for explaining the operation of an ink jet recording head. FIG. 4 is a diagram for explaining the operation of an ink jet recording head. FIG. 9 is a schematic configuration diagram of an ink jet printer according to a third embodiment. The schematic sectional drawing of the piezoelectric pump which concerns on 4th Embodiment. The schematic sectional drawing of the piezoelectric pump which concerns on 4th Embodiment. FIG. 10 is a side sectional view showing a surface acoustic wave device according to a fifth embodiment. The perspective view which shows the frequency filter which concerns on 6th Embodiment. The perspective view which shows the oscillator which concerns on 7th Embodiment. Schematic which shows an example which applied the oscillator concerning 7th Embodiment to VCSO. Schematic which shows an example which applied the oscillator concerning 7th Embodiment to VCSO. Schematic which shows an example which applied the oscillator concerning 7th Embodiment to VCSO. The block diagram which shows the basic composition of a PLL circuit. The block diagram which shows the structure of the electronic circuit which concerns on 8th Embodiment. FIG. 10 is a side sectional view showing a thin film piezoelectric resonator according to a ninth embodiment. FIG. 10 is a side sectional view showing a thin film piezoelectric resonator according to a ninth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate, 2 Stopper layer, 3 Hard layer, 4 First conductive layer, 5 Piezoelectric layer, 6 Second conductive layer, 10 Piezoelectric element, 11 Substrate, 14 First conductive layer, 15 Piezoelectric layer, 16 Second conductive Layer, 17 protective layer, 18 substrate, 20 piezoelectric pump, 21 substrate, 22 piezoelectric part, 23 pump chamber, 24 diaphragm, 30 surface acoustic wave element, 40 low resistance layer, 41 buffer layer, 42 conductive oxide layer, 46 Second conductive oxide layer, 47 Second low resistance layer, 50 Inkjet recording head, 51 Nozzle plate, 52 Ink chamber substrate, 54 Piezoelectric section, 55 Elastic layer, 56 Base, 57 Head body, 58 Ink droplet, 60 housing Body, 61 substrate, 63 oscillator, 64 base, 66 wiring, 67 wire, 70 input terminal, 71 phase comparator, 72 low-pass filter, 73 amplifier, 80 transmitter, 81 Transmission signal processing circuit, 82 transmission mixer, 83 transmission filter, 84 transmission power amplifier, 85 transmission / reception demultiplexer, 86 antenna unit, 87 low noise amplifier, 88 reception filter, 89 reception mixer, 90 reception signal processing circuit, 91 reception unit , 92 Frequency synthesizer, 93 control circuit, 94 input unit, 95 display unit, 140 substrate, 141 IDT electrode, 142 IDT electrode, 143 sound absorption unit, 144 sound absorption unit, 145 high frequency signal source, 150 substrate, 151 IDT electrode, 152 IDT Electrode, 153 IDT electrode, 154 High-frequency signal source, 300 Electronic device, 310 Electronic circuit, 511 nozzle, 521 Ink cavity, 522 Side wall, 523 Reservoir, 524 Supply port, 531 Communication hole, 600 Inkjet printer, 620 Device body, 621 G A, 622 Discharge port, 630 Head unit, 631 Ink cartridge, 632 Carriage, 640 Printing device, 641 Carriage motor, 642 Reciprocating mechanism, 643 Carriage guide shaft, 644 Timing belt, 650 Paper feeding device, 651 Paper feeding motor, 652 Feed roller, 660 control unit, 670 operation panel, 700 first thin film piezoelectric resonator, 701 substrate, 702 via hole, 703 elastic layer, 704 first conductive layer, 705 piezoelectric layer, 706 second conductive layer, 708 wiring , 709 electrode, 710 pad, 800 second thin film piezoelectric resonator, 801 substrate, 802 air gap, 803 elastic layer, 804 first conductive layer, 805 piezoelectric layer, 806 second conductive layer

Claims (20)

  A low resistance layer including a conductive material having a specific resistance lower than that of the lanthanum layered perovskite compound, and a buffer layer formed on the low resistance layer and including a lanthanum layered perovskite compound preferentially oriented to (001). 1 conductive layer;
  A piezoelectric layer including a piezoelectric body formed on the buffer layer and having a perovskite structure preferentially oriented to (001);
  And a second conductive layer formed on the piezoelectric layer.   In claim 1,
  The lanthanum layered perovskite compound is La ₃ Ni ₂ O ₇ A piezoelectric element.   In claim 1,
  The lanthanum layered perovskite compound is La ₄ Ni ₃ O ₁₀ A piezoelectric element.   In claim 1,
  The lanthanum layered perovskite compound is La ₂ CuO ₄ A piezoelectric element.   In any one of Claims 1-4,
  The piezoelectric element, wherein the buffer layer has a thickness of 10 nm to 50 nm.   In any one of Claims 1-5,
  A piezoelectric element, wherein the A site of the lanthanum-based layered perovskite compound is substituted with 10 at% or less of Pb.   In any one of Claims 1-6,
  The piezoelectric element, wherein the low resistance layer has a thickness of 50 nm to 150 nm.   In any one of Claims 1-7,
  The low resistance layer is a (111) oriented piezoelectric element.   In any one of Claims 1-8,
  The piezoelectric element is a piezoelectric element including Pb.   In any one of Claims 1-9,
  The piezoelectric element is a piezoelectric element that is a rhombohedral crystal or a mixed crystal of a tetragonal crystal and a rhombohedral crystal. A piezoelectric element according to any one of claims 1-10, the piezoelectric actuator. A piezoelectric element according to any one of claims 1-10, piezoelectric pump. A piezoelectric element according to any one of claims 1-10, an ink jet recording head. An ink jet printer comprising the ink jet recording head according to claim 13 . A piezoelectric element according to any one of claims 1-10, the surface acoustic wave device. A piezoelectric element according to any one of claims 1-10, a thin film piezoelectric resonator. A frequency filter comprising at least one of the surface acoustic wave device according to claim 15 and the thin film piezoelectric resonator according to claim 16 . An oscillator comprising at least one of the surface acoustic wave device according to claim 15 and the thin film piezoelectric resonator according to claim 16 . An electronic circuit comprising at least one of the frequency filter according to claim 17 and the oscillator according to claim 18 . An electronic apparatus comprising at least one of the piezoelectric pump according to claim 12 and the electronic circuit according to claim 19 .

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